LOGIN_REQD error on GetAll on SalesTaxItems

I am making a simple getAll call for the SalesTaxItems and it works fine on my test portal however on the customer portal, we get a LOGIN_REQD error when retrieving the list.

We can access other aspects of the customer portal just fine via Web services.  However, this one simple call fails with a login error.

Any ideas?

Thanks in advance. (Here's the .NET code:)

            GetAllRecord gar = new GetAllRecord();
            gar.recordType = GetAllRecordType.salesTaxItem;
            gar.recordTypeSpecified = true;
            GetAllResult res = Service.getAll(gar);